Why is the Standard Deviation of portfolios in the Personal edition of Steele Expert blank?

For the standard deviation of portfolios to be calculated, monthly return data is needed going back at least three years. The Personal edition only has 1 year (12 months) of monthly returns and that is why the 3-year standard deviation shows as blank.

The reason is that the standard deviation of a portfolio of securities (mutual funds, stocks, bonds, etc.) is not the arithmetic mean of the standard deviation of each of the securities, but must be computed by using the actual monthly returns of the portfolio itself.

The Pro and Pro Plus versions do have monthly return data going back 10 and 43 years respectively, and do allow for the correct computation of the standard deviation of portfolios.